[morzh]

Try Deoxit D5 first, it seems like this type of switches is not sealed very well so it will penetrate - use the spaces around actuators. Unless the contacts are on the surface in the open - I am not sure what I am seeing tehre. If in the open - desolder, soak in mineral spirits, brush.....lots of grime there. Acetone might work too, if it is not plastic but a fenolic board. Of course do it outside, don't inhale.
Then once it dries, use Deoxit F5 - the fadder lube, it will take care of friction.
Other switches....try the same first. If it does not help - then, ok, look for a donor chassis.